Core-shell nanowire, method for synthesizing the core-shell nanowire, and transparent electrode and organic light emitting diode including the core-shell nanowire

ABSTRACT

A metal (or core-shell) nanowire and a method for manufacturing the same, and a transparent electrode and an organic light emitting diode including the metal (or core-shell) nanowire having a high electric conductivity, a suitable transmittance and a suitable haze are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage application of InternationalApplication No. PCT/KR2015/000803 filed on Jan. 26, 2015, the entiredisclosure of which is incorporated herein by reference for allpurposes.

TECHNICAL FIELD

The present invention relates to a core-shell nanowire and a method formanufacturing the same and to a transparent electrode and an organiclight emitting diode including the core-shell nanowire.

BACKGROUND ART

Recently, as technology of a display device and a solar cell progresses,demand for a transparent electrode used for the display device and thesolar cell rapidly increases. An indium tin oxide (ITO) is generally toa material of the transparent electrode because the ITO is suitable fora mass production technique and for being used for the display deviceand the solar cell. However, a manufacturing cost of the ITO electrodeis very high due to a vacuum process, and the ITO electrode is notstable to an external shock such as a thermal shock. Thus, a materialreplacing the ITO electrode is developing.

For materials replacing the ITO electrode, there are conductive polymerssuch as carbon nanotube (CNT), graphene, a zinc oxide (ZnO),poly(3,4-ethylenedioxythiophene) (PEDOT), and so on, a metal nanowire,and the like.

The metal nanowire, more particularly, a silver nanowire among them hasa high chemical stability. The silver nanowire has properties of silverhaving high thermal conductivity and high electric conductivity and anoptical property being transparent induced by the nanowire having a verysmall size. Thus, the metal nanowire, more particularly, the silvernanowire is in the spotlight as a metal material for manufacturing atransparent conductive film. The silver nanowire may be widely appliedto electronic, magnetic, and optical elements or devices and sensors,such as, a plasma display panel (PDP), an optical filter, anelectromagnetic wave shield, an organic Light emitting diode (OLED), asolar cell, a liquid crystal display (LCD), a touch screen, an EL keypad for a cellular phone, and so on for the future.

The metal nanowire may be manufactured by a synthesizing method, knownas a polyol method. In the polyol method, the metal salt is reduced to ametal atom by a polyol solvent (refer to US Laid-open Patent PublicationNo. 2005/0056118). Generally, the reduced metal atom initially formsseeds through a homogeneous nucleation process. And then, some of seedsgrows in all direction in the solution and forms isotropicnano-structures (nanoparticles), and other seeds firstly grows accordingto a direction of a side surface and forms anisotropic nano-structures(nanotubes, nanowire portions, nano-belts, nanowires, and so on).

Recently, several studies for a flexible-substrate conductor using ametal nanowire are continued and a commercialization thereof is achievedto some agree. However, an electric resistance at contact points betweennanowires may increase due to sulfidation and an oxidation, and anelectric property may be bad. Thus, it may be a fatal defect for adevice where reliability is needed.

In the past, studies for increasing an electric conductivity andreducing a haze were progressed, considering that the metal nanowire isused for a conductive material of a display device. However, a study forincreasing light-scattering to have light extraction was not suggested.

DISCLOSURE

Terms, phrases, or expressions used in the specification are only fordescribing embodiments, not for limiting the scope and spirit of theinvention. All of technical terms and scientific terms have meanings thesame as meanings generally understood by the skilled person in the artso long as there is no special conflicting description.

In the entire specification, when an element, or a method or a step isreferred to as “comprise”, “comprising”, “includes” or “including”another element or step, the element should not be understood asexcluding other elements or steps so long as there is no specialconflicting description, and the element may include at least one otherelement or step.

On the other hand, embodiments of the invention may be combined with theother embodiments so long as there is no special conflictingdescription. Particularly, preferable properties, structures, elements,or structures may be combined with the other properties, structure,elements, or structures. Hereinafter, embodiments of the invention andeffects thereof will be described in detail with reference to theaccompanying drawings.

Technical Problem

The invention has been made in view of the above problems, and it is anobject of the invention to provide a metal nanowire having a largediameter and a large aspect ratio and including a plurality of wireportions having at least one bent portion. Thus, a contact probabilitybetween the metal nanowires can increase, an increase of a sheetresistance can be prevented, and an electric conductivity can besuperior. Particularly, when the metal nanowire is used for atransparent electrode (particularly, for an OLED lighting, an organicsolar cell, and so on), the transparent electrode has a transmittanceand a haze suitable for the OLED lighting or the organic solar cell.

Also, it is another object of the invention to provide a metal nanowirehaving a large diameter and a large aspect ratio and having differentdiameters. Thus, a contact probability between the metal nanowires canincrease, an increase of a sheet resistance can be prevented, and anelectric conductivity can be superior. Particularly, when the metalnanowire is used for a transparent electrode (particularly, for an OLEDlighting, an organic solar cell, and so on), the transparent electrodehas a transmittance and a haze suitable for the OLED lighting or theorganic solar cell.

In addition, it is yet another object of the invention to provide acore-shell nanowire having a metal coating. A sulfidation and anoxidation can be prevented and reliability can be enhanced. Alight-scattering property can be enhanced, and a high haze can beachieved without largely reducing an electric conductivity and atransmittance.

Further, it is still another object of the invention to provide a methodfor manufacturing a metal nanowire having a large diameter and a largeaspect ratio and including a plurality of wire portions having at leastone bent portion with a high yield without by-products other than themetal nanowire.

Furthermore, it is yet still another object of the invention to providea method for manufacturing a metal nanowire having a large diameter anda large aspect ratio and having different diameters with a high yieldwithout by-products other than the metal nanowire.

Also, it is yet still another object of the invention to provide amethod for manufacturing a core-shell nanowire having a metal coating.

Further, it is yet still another object of the invention to provide atransparent electrode and an organic light emitting diode including ametal nanowire having a large diameter and a large aspect ratio andincluding a plurality of wire portions having at least one bent portionas a conductor layer. Thus, an electric conductivity can be superior.Particularly, the transparent electrode has a transmittance and a hazesuitable for an OLED lighting or an organic solar cell.

In addition, it is yet still another object of the invention to providea transparent electrode and an organic light emitting diode including ametal nanowire having a large diameter and a large aspect ratio andhaving different diameters as a conductor layer. Thus, an electricconductivity can be superior. Particularly, the transparent electrodehas a transmittance and a haze suitable for an OLED lighting or anorganic solar cell.

Furthermore, it is yet still another object of the invention to providea core-shell nanowire having a metal coating as a conductor layer. Asulfidation and an oxidation can be prevented and reliability can beenhanced. A light-scattering property can be enhanced, and a high hazecan be achieved without largely reducing an electric conductivity and atransmittance.

Technical Solution

A core nanowire according to an embodiment includes a nanowire core; anda metal-compound shell formed on the nanowire core.

(1) A Metal Nanowire

1) A Metal Nanowire Including a Plurality of Wire Portions Having atLeast One Bent Portion

A metal nanowire according to an embodiment of the invention includes atleast two wire portions (or at least one bent portion). Moreparticularly, the metal nanowire includes at least one wire portionconnected to another wire portion through the bent portion. An angle (α)between an n-th wire portion and an (n+1)-th wire portion connected tothe n-th wire portion through an n-th bent portion satisfies aninequation of 0°<α<180°.

For example, when the metal nanowire includes two wire portions, a firstwire portion and a second wire portion connected to the first wireportion through a first bent portion have an angle (α) therebetween, asshown in FIG. 1. As another example, the metal nanowire may include aplurality of wire portions, as shown in FIG. 2.

More particularly, the angle (α) between the n-th wire portion and the(n+1)-th wire portion connected to the n-th wire portion through then-th bent portion satisfies an inequation of 130°≤α≤170°. When the metalnanowires are synthesized by a method for manufacturing a metal nanowireincluding the plurality of wire portions having at least one bentportion according to the invention that will be described later,although some metal nanowires having at least one bent portion with anangle of 90° or less are formed among the metal nanowires having twowire portion (or one bent portion), almost metal nanowires have two tofour wire portions (or one bent portion to three bent portions) and theangle of the bent portion is in a range of 130° to 170°.

In the metal nanowire including the wire portions having the bentportion according to the invention, when the metal nanowire issynthesized, as crystals are grown, strain increases in order to releasestress generated by a gravity applied to grown sites of the metalnanowire. Accordingly, the metal nanowire has a structure bent in apredetermined direction to have a predetermined angle. When at least onebent portion has the predetermined angle, contact points, contact areas,or a contact probability between the metal nanowires can increase.Accordingly, an electric conductivity of a transparent electrode or aconductor layer formed of the metal nanowires according to theembodiment can be superior, compared with a transparent electrode or aconductor layer formed or a metal nanowire having a shape of a straightline.

Also, the metal nanowire according to the embodiment of the inventionhas a two-dimensional or three-dimensional structure. When a planeincluding the n-th wire portion and the (n+1)-th wire portion is an Aplane and a plane including the (n+1)-th wire portion and an (n+2)-thwire portion is a B plane, an angle (β) of the B plane with respect tothe A plane is in a range of −10° to 10°. FIG. 3 illustrates a metalnanowire having a three-dimensional structure according to anotherembodiment of the invention.

The metal nanowire including the wire portions having the bent portionaccording to an embodiment of the invention has a diameter of 50 to 200nm and a length of 40 to 300 μm. In the present specification, thediameter of the metal nanowire indicates a longest length of the metalnanowire in a horizontal cross section of the metal nanowire, and thelength of the metal nanowire indicates a longest length of the metalnanowire in a longitudinal cross section of the metal nanowire. Also,the metal nanowire has an aspect ratio is in a range of 200 to 6000. Theaspect ratio is a ratio (length/diameter) of the length to the diameter.

The metal nanowire including the wire portions having the bent portionaccording to the embodiment of the invention has a large diameter of 50to 200 nm, and thus, the metal nanowire is grown to be bent, not to bebroken, even the stress above a predetermined value is applied to themetal nanowire when the metal nanowire is synthesized. Also, since themetal nanowire has a long length of 40 to 300 μm, the metal nanowire hasthe at least one bent portion. In addition, the metal nanowire is bentin a predetermined direction (that is, a gravity direction).Accordingly, when the metal nanowire has two or more bent portions, themetal nanowire has a bent curve structure, not a zigzag structure.

Also, contact areas between the metal nanowires, each having thediameter, the length, and the aspect ratio of the above ranges, arelarger than contact areas between metal nanowires, each has a sizesmaller than the above ranges. Thus, an electric conductivity of atransparent electrode or a conductor layer formed of the metal nanowiresaccording to the embodiment can be superior. Therefore, the metalnanowire can be suitable for a material of a transparent electrode.

The metal nanowire according to the embodiment of the invention may be ananowire of a metal material including Ni, Co, Fe, Pt, Au, Ag, Al, Cr,Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti, W, U, V, Zr, Ge, and so on. The metalnanowire of silver (Ag) has a high chemical stability among variousmetals, has greatly superior thermal conductivity and electricconductivity, and has a transparency, which is an optical property shownby a small size of a nanowire. Thus, the metal nanowire can be suitablefor a metal material for manufacturing a transparent conductive layer.

In addition, the metal nanowire (particularly, the silver nanowire)according to the embodiment of the invention can be widely applied toelectronic, magnetic, and optical elements or devices and sensors, suchas, a plasma display panel (PDP), an optical filter, an electromagneticwave shield, an organic Light emitting diode (OLED), a solar cell, aliquid crystal display (LCD), a touch screen, an EL key pad for acellular phone, and so on.

2) A Metal Nanowire Having Different Diameters

The metal nanowire according to another embodiment of the inventionincludes a plurality of wire parts having different diameters. Forexample, the metal nanowire includes a first wire part and a second wirepart extended from the first wire part. The first wire part has adiameter (a first diameter) of 50 to 100 nm and a length of 40 to 100μm, and the second wire part has a diameter (a second diameter) of 150to 1100 nm and a length of 5 to 15 μm. FIG. 4 illustrates a metalnanowire including a plurality of wire parts having different diametersaccording to yet still another embodiment of the invention.

Also, in the metal nanowire according to the embodiment of theinvention, the second diameter is two times to fifteen times the firstdiameter. When the second diameter is below two times the firstdiameter, a light-scattering effect may be less. When the seconddiameter is above fifteen times the first diameter, the transmittance ofa transparent electrode may be reduced and the dispersibilty may bereduced in a case that the metal nanowire can be suitable for thetransparent electrode. Preferably, the second diameter may be two timesto five times the first diameter.

The second wire part may be formed at one end or two ends of the firstwire part. Also, two or more second wire parts may be formed at each endof the first wire part. FIG. 5 illustrates a metal nanowire including aplurality of wire parts having different diameters according to anotherembodiment of the invention, wherein (a) illustrates the metal nanowirehaving the second wire part formed at one end and (b) illustrates themetal nanowire having the second wire parts formed at both ends. Thus,the metal nanowire has an increased contact area with another metalnanowire by the second wire portion, and thus, the metal can be suitablefor a metal material for manufacturing a transparent conductive layer.

A cross section of one of each of the first wire part and the secondwire part perpendicular to a longitudinal direction of the metalnanowire may have a polygonal shape, for example, a triangular shape, aquadrangular shape, a pentagonal shape, and so on. However, theembodiment is not limited thereto.

When the metal nanowire having the plurality of wire parts havingdifferent diameters according to the embodiment of the invention is usedfor a conductor layer of a transparent electrode, a transparency is 80%or more. Thus, the metal nanowire can have properties suitable for anOLED lighting.

Also, when the metal nanowire including the plurality of wire partshaving different diameters according to the embodiment of the inventionis used for the conductor layer of the transparent electrode, a haze is1% or more, and a light extraction can be induced through alight-scattering effect. Accordingly, when the metal nanowire is usedfor the OLED lighting, efficiency of the OLED lighting can be enhanced.

When the conventional metal nanowire having a uniform diameter generallyhas a low haze of 1% or less, there is almost never the light-scatteringeffect. On the other hand, the metal nanowire including the second wirepart according to the embodiment has a light-scattering effect and has alarge haze.

In addition, the conventional metal nanowire has a large surface areaeven the conventional metal a small weight and volume, and thus, may beeasily aggregated. Thus, when the conventional metal nanowire isgenerally used for the transparent electrode, the dispersibilitydecreases and a sheet resistance (Ω/□) increases. Meanwhile, the metalnanowire including the second wire part according to the embodiment canhave a superior dispersibility and the sheet resistance of the metalnanowire can be prevented.

3) A Metal Nanowire Including a Plurality of Wire Portions Having atLeast One Bent Portion and Having Different Diameters

The metal nanowire including a plurality of wire portions having atleast one bent portion may include wire portions having diametersdifferent from each other, or may include at least one wire portionhaving multiple diameters. The wire portion may include a plurality ofwire parts having different diameters. That is, the metal nanowireincluding the plurality of wire portions having at least one bentportion has at least two different diameters. Accordingly, the wireportions of the metal nanowire according to the embodiment of theinvention may include a wire portion having a single diameter of a firstdiameter, a wire portion having a single diameter of a second diameter,and/or the wire portion having the multiple diameters.

The wire portion having the single diameter has a first diameter of 500to 200 nm and/or a second diameter of 150 to 1100 nm. The wire portionhaving the multiple diameters may have both of the first diameter of 50to 200 nm and the second diameter of 150 to 1100 nm. FIG. 6 illustratesthe wire portions according to embodiments of the invention, and FIG. 7illustrates the metal nanowire according to embodiments of theinvention.

The second diameter is two times to fifteen times the first diameter.When the second diameter is below two times the first diameter, alight-scattering effect may be less. When the second diameter is abovefifteen times the first diameter, the transmittance of a transparentelectrode may be reduced and the dispersibilty may be reduced in a casethat the metal nanowire is used for the transparent electrode.Preferably, the second diameter may be two times to five times the firstdiameter.

The wire portion including the second diameter may be generally includedat an end of the metal nanowire. However, the embodiment is not limitedthereto. According to an amount of a capping agent when the metalnanowire is synthesized, the wire portion having the multiple diametersmay be formed at an arbitrary position or a position other than the endof the metal nanowire.

As another aspect, at least one of wire portions of the metal nanowirehaving different diameters has a bent portion. Referring to FIG. 8, awire portion or a wire part having a first diameter or a wire portion ora wire part having a second diameter has a shape of a straight line orhas a bent portion.

When the wire portion or the wire part has the bent portion, a bentangle (α) satisfies an inequation of 130°≤α≤170°. FIG. 8 illustratesvarious wire parts according to embodiments and FIG. 9 illustratesvarious metal nanowires according to embodiments of the invention whenthe nanowire includes two wire portions.

4) A Core-Shell Nanowire Having a Metal Coating

The core-shell nanowire according to an embodiment of the inventionincludes a nanowire core and a metal-compound shell coated on thenanowire core.

The nanowire core may be a conductive metal nanowire, for example, asilver (Ag) nanowire. Various commercialized or marketed metal nanowiresmay be unlimitedly used for the nanowire core. Preferably, the metalnanowire including the plurality of wire portions having the at leastone bent portion, and the metal nanowire having different diameters, andthe metal nanowire including the plurality of wire portions having theat least one bent portion and having different diameters may be used forthe nanowire core.

For example, a cross section of the nanowire core perpendicular to alongitudinal direction of the nanowire core may have a polygonal shape,for example, one of a triangular shape, a quadrangular shape, apentagonal shape, a hexagonal shape, and so on. However, the embodimentis not limited to the shape of the nanowire core. When the cross sectionof the nanowire core has the polygonal shape, the metal-compound shellcan be coated so that the light-scattering property can be enhancedmore.

The nanowire core has a diameter of 30 to 200 nm and a length of 10 μmto 300 μm. When the nanowire core is the metal nanowire including theplurality of wire portions having the at least one bent portionaccording to the embodiment, the nanowire core has a diameter of 50 to200 nm and a length of 40 μm to 300 μm. When the nanowire core havingdifferent diameters according to the embodiment, the nanowire core hasthe first diameter of 50 to 100 nm and the second diameter of 150 nm to1100 nm, and a length of 5 μm to 15 μm.

The metal-compound shell is coated on the nanowire core to surround thenanowire core. The embodiment is not limited to a material of themetal-compound shell. However, the metal-compound shell may bepreferably transparent, and may include a transparent conductive metaloxide, nitride, sulfide, or so on. For example, the transparentconductive metal-compound shell may include at least one of ZnO, SiO2,SnO₂, TiO₂, AlN, GaN, BN, InN, ZnS, CdS, ZnSe, ZnTe, CdSe, and acompound including carbon, and may be further include a dopant forhaving an electric conductivity. The transparent conductivemetal-compound shell may be formed of one material or be formed of analloy or a mixture having several materials. The transparent conductivemetal-compound shell may have a single-layer structure or amultiple-layer structure.

In the conventional technology, the light-scattering of the nanowireshould be less with consideration of the optical property, and the hazeof the conductive layer formed of the nanowire should be small. However,in the embodiment of the invention, the core-shell nanowire having anincreased light-scattering effect and a high haze value is suggested,contrary to the conventional technology.

In the embodiment, the light-scattering effect can be remarkablyincreased since a core-shell structure is introduced in order toincrease the light scattering of the nanowire and the shell has astructure having an unprecedented protruded structure having a uniqueshape.

As an example, the metal-compound shell includes a plurality ofprotruded structures in a cross section perpendicular to a longitudinaldirection of the core-shell metal nanowire. The protruded structure mayhave a shape where an area or a width gradually decreases as thedistance from the nanowire core increases. The number of the protrudedstructures may be 3 to 6. However, the invention is not limited thereto.The expression of “the protruded structure may have a shape where anarea or a width gradually decreases as the distance from the nanowirecore increases” may be interpreted in a broad sense. That is, the phraseimplies may include a case that 70% or more of the protruded structurehas the shape where the area or the width gradually decreases as thedistance from the nanowire core increase although the protrudedstructure partially has a portion which area or a width graduallyincrease as the distance from the nanowire core increases.

As another example, the metal-compound shell when viewed in the crosssection perpendicular to the longitudinal direction of the core-shellnanowire may have a shape of a plurality of polygons. The number of thepolygons may be 3 to 6. However, the invention is not limited thereto.The “polygons” may be interpreted in a broad sense. The “polygons” mayinclude a shape similar to a polygon that is generally recognized as thepolygon as well as a shape of an exact polygon in the cross section.

As yet another example, the metal-compound shell may a stripe patternhaving a plurality of portions extending a longitudinal direction of thecore-shell nanowire. The number of the plurality of portionsconstituting the stripe pattern may be three to six. However, theinvention is not limited thereto.

As concrete examples, FIG. 10 to FIG. 13 illustrate core-shell nanowiresaccording to embodiments of the invention. As shown in FIG. 10 to FIG.13, a metal-compound shell 20 is coated on the nanowire core 10. Themetal-compound shell 20 has a shape where metal-compound oxides areaggregated to each other. Metal-compound particles 21 may have diameters(e) in a range of 10 to 100 nm. However, the embodiment is not limitedthereto.

As shown in FIG. 10, when viewed in the cross section perpendicular tothe longitudinal direction of the metal nanowire, the metal-compoundshell 20 has four triangular shapes to four stripe patterns. That is,each of the four triangular shapes extends in the longitudinal directionof the core-shell nanowire.

Selectively, as shown in (a) of FIG. 11, when viewed in the crosssection perpendicular to the longitudinal direction of the metalnanowire, the metal-compound shell 20 has five triangular shapes to fivestripe patterns. That is, each of the five triangular shapes extends inthe longitudinal direction of the core-shell nanowire. As shown in (b)of FIG. 11, when viewed in the cross section perpendicular to thelongitudinal direction of the metal nanowire, the metal-compound shell20 has six triangular shapes to six stripe patterns. That is, each ofthe six triangular shapes extends in the longitudinal direction of thecore-shell nanowire.

Meanwhile, as shown in FIG. 12, when viewed in the cross sectionperpendicular to the longitudinal direction of the metal nanowire, themetal-compound shell 20 has five trapezoid shapes to five stripepatterns. That is, each of the five trapezoid shapes extends in thelongitudinal direction of the core-shell nanowire. By changingconditions of a method for forming the metal-compound shell, thetriangular shape or the trapezoid shape can be manufactured. Forexample, even the process conditions for forming the triangular shape isapplied, the metal-compound shell 20 can have the trapezoid shape byinsufficient process conditions, such as, short time or a small amountof precursors (refer to FIG. 13).

When a side of the polygon adjacent to the nanowire core is a bottomside (d) of the polygon, the bottom side (d) of the polygon may has alength of 40 nm to 200 nm and the polygon has a height of 10 nm to 200nm. When the height of the bottom side is below the range, thelight-scattering effect may be less. When the length of the bottom sideand/or the height is above the range, light loss due to the lightabsorption may increase.

The length (a) of the core-shell nanowire is not limited. For example,the length (a) may be in a range of 10 μm to 200 μm, and a ratio (c/a)of the height (c) of the polygon to the length (a) of the core-shellnanowire may be in arrange of 0.00006 to 0.02. In addition, when viewedin the cross section of the core-shell nanowire perpendicular to alongitudinal direction of the core-shell nanowire, a ratio (longestdiameter/length) of the longest diameter of the core-shell nanowire tothe length (a) of core-shell nanowire may be in a range of 0.0001 to0.06. By the above structure, light of various wavelengths can bescattered.

The core-shell nanowire having the above structure has a superiorlight-scattering property. The haze detected when the core-shellnanowire is coated on a transparent substrate may be 3% or more at awavelength of 550 nm, and, preferably, 20% or more at the wavelength of550 nm. The haze may be 60% or more, as in following Embodiments.

Also, the sheet resistance of the coated layer including the core-shellnanowire is superior, for example, 60 (Ω/□) or less. The sheetresistance of the coated layer including the core-shell nanowireaccording to the embodiment is not largely worse than the sheetresistance of the coated layer including the metal nanowire that is notcoated. Also, the sheet resistance of the coated layer including thecore-shell nanowire according to the embodiment may lower than the sheetresistance of the coated layer including the metal nanowire that is notcoated. In addition, the light transmittance at the wavelength of 550 nm(excepting for a substrate absorption) can be high, for example, 70 to98%.

When the core-shell nanowire according to the embodiment of theinvention is used for a conductor layer of a transparent electrode, atransmittance of the conductor layer of the transparent electrode is 80%or more. Thus, the core-shell nanowire can have properties suitable foran OLED lighting.

Also, when the core-shell nanowire according to the embodiment of theinvention is used for the conductor layer of the transparent electrode,a haze is 1% or more, and a light extraction can be induced through alight-scattering effect. Accordingly, when the conductor layer of thetransparent electrode including the metal nanowire is used for the OLEDlighting, efficiency of the OLED lighting can be enhanced.

In addition, the conventional metal nanowire has a large surface areaeven the metal nanowire has a small weight and volume, and thus, theconventional metal nanowire may be easily aggregated. Thus, when theconventional metal nanowire is generally used for the transparentelectrode, the dispersibility decreases and a sheet resistance (Ω/□)increases. Meanwhile, the core-shell nanowire according to theembodiment can have a superior dispersibility and the increase of asheet resistance can be prevented.

(2) A Method for Manufacturing a Metal Nanowire

1) A Method for Manufacturing a Metal Nanowire Including a Plurality ofWire Portions Having at Least One Bent Portion

In a method for manufacturing a metal nanowire including a plurality ofwire portions having at least one bent portion according to anembodiment of the invention, all materials of a reaction mixture areadded to a reaction container and a synthesized reaction is performed ata pressure of an atmospheric pressure or a pressure higher than theatmospheric pressure (for example, 1 to 5 atm) to manufacture the metalnanowire including the plurality of wire portions having the at leastone bent portion.

The manufacturing method according to the embodiment of the inventioncan synthesize a metal nanowire having a diameter of 50 to 200 nm and alength of 40 to 300 μm. The metal nanowire is grown to be bent, not tobe broken, even the stress above a predetermined value is applied to themetal nanowire when the metal nanowire is synthesized. And thus, themetal nanowire including at least two wire portions connected throughthe at least one bent portion can be manufactured.

In addition, the method is an one-pot synthesis. In the one-potsynthesis, a purification of intermediate products is not necessary, andthe metal nanowire including at least two wire portions having the atleast one bent portion can be manufactured with a high yield withoutby-products other than the metal nanowire.

More particularly, the method for manufacturing the metal nanowire mayinclude a step S10 of preparing a reaction mixture and a step S20 ofsynthesizing a metal nanowire. In the step S10 of preparing the reactionmixture, the reaction mixture including a metal salt, a capping agent, areducing solvent, and a catalyst are prepared. In the step S20 ofsynthesizing the metal nanowire, the metal nanowire is grown by addingthe reaction mixture to a reaction container and reacting with thereaction mixture in the reaction container. By controlling a compositionand an amount of the reaction mixture, a reaction temperature, areaction pressure, a reaction time, and so on, the metal nanowireincluding the plurality of wire portion having at least one bent portionwith a large diameter and a large aspect ratio can be synthesized.

In the step S10 of preparing the reaction mixture, the reaction mixtureis prepared by adding the metal salt, the capping agent, the reducingsolvent, and the catalyst to the reaction container with a predeterminedratio and mixing them in the reaction container at a room temperature.The reducing solvent reduces the metal salt to a metal. The cappingagent grows the reduced metal to have a wire shape.

The metal salt is a compound consisting of metal cation and organic orinorganic anion. For example, the metal cation may be a cation of ametal of Ni, Co, Fe, Pt, Au, Ag, Al, Cr, Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti,W, U, V, Zr, Ge, and so on. The organic or inorganic anion may be[NO₃]⁻, [ClO₄]⁻, [BF₄]⁻, [PF₆]⁻, [CH₃COO]⁻, [CF₃SO₃]⁻, [SO₄]²⁻,[CH3COCH═COCH3]⁻, and so on. Two or more metal salts having similarionization degrees may be mixed and the mixed metal salts may be used.Preferably, a silver salt consisting of cation of silver (Ag⁺) and theorganic or inorganic anion may be used.

The metal salt is dissolved by the reducing solvent, and is decomposedto the metal cation and the organic or inorganic anion. The decomposedmetal cation is reduced, and then, is crystallized or grown to the metalnanowire.

A molar concentration of the metal salt is 0.03 mol/l to 0.4 mol/l. Whenthe molar concentration is below 0.03 mol/l, an output of generatedmetal nanowire rapidly decreases. When the molar concentration is above0.4 mol/l, the wires may be aggregated by an overproduction. Morepreferably, the molar concentration of the metal salt may be 0.05 mol/lto 0.10 mol/l.

The reducing solvent may be a polar solvent being able to dissolve themetal salt, the catalyst, and the capping agent. The reducing solventhas at least two hydroxyl groups in molecule. For example, a solventsuch as a diol, a polyol, a glycol, or so on may be used. The reducingsolvent acts as a reducing agent, and reduces the metal salt and forms ametal. As an example, at least one of ethyleneglycol, propyleneglycol,and glycerol may be used, More particularly, at least one ofethyleneglycol, 1, 2-propyleneglycol, 1, 3-propyleneglycol, glycerin,glycerol and diethylglycol may be used.

The capping agent is a chemical agent firstly interacting with sidesurfaces of the grown nanowire and being attached to the side surfacesof the grown nanowire so that a surface of a horizontal cross section ofthe nanowire can be crystallized. That is, the capping agent interactswith the side surface stronger than the surface of the horizontal crosssection. Thus, the side surfaces are passivated, while the surface ofthe horizontal cross section is additionally crystallized to produce thenanowire.

For the capping agent, a surface-attached polymer such aspolyvinylpyrrolidone (PVP), polyvinylalcohol (PVA), polyacrylamide(PAM), polyacrylicacid (PAA), and so on may be used.

The capping agent is included in an amount of 0.5 to 3.0 parts by weightwith respect to 28 parts by weight of the reducing solvent. When thecapping agent is included below 0.5 parts by weight, the diameter of themetal nanowire may increase. When the capping agent is included above3.0 parts by weight, the length of the metal nanowire may largelydecrease. The capping agent may be included by 2.0 to 3.0 parts byweight with respect to 28 parts by weight of the reducing solvent.

The catalyst is a salt additive including a cation and an anion bondedto each other through an ionic bond. The catalyst is separated to ionsin the polar solvent such as water, an alcohol, a diol, and a polyol. Inthis instance, a cation may be an organic material or an inorganicmaterial, and an anion may be generally an inorganic material and has ahalogen ion (Cl⁻, Br⁻, F⁻, or so on). Anisotropy nano structures arefirstly grown by the catalyst, thereby obtaining the nanowire with arelatively high yield.

The catalyst may include at least one of a compound where a cation andan anion bonded to each other through an ionic bond and a hydratethereof. The cation may be a cation of Al, NH₄, Sb, As, Ba, Bi, Cd, Ca,Cr, Co, Cu, Fe, H, Pb, Mg, Hg, Ni, K, Ag, Na, Sr, and/or Zn. The anionmay be an anion of C₂H₃O₂, Br, CO₃, Cl, CrO₄, OH, I, NO₃, O, C₂O₄, PO₄,SIO₃, SO₄, S, and/or SO₃.

A molar concentration of the catalyst may be in a range of 10⁻⁵ mol/l to10⁻² mol/l. When the molar concentration is below 10⁻⁵ mol/l, thegeneration of the metal nanowire may be declined by a reduction of aninitial nucleation. When the molar concentration is above 10⁻² mol/l, amacro-aggregation may be induced or the surplus catalyst prevents ananisotropic growth of the metal nanowire, the diameter increases, and ageneration of spherical particles may increase.

In the step S20 of synthesizing the metal nanowire, the preparedreaction mixture is reacted in the reaction container. Then, the crystalgrows to the metal nanowire through reducing the metal cation andgrowing crystals from metal nucleation sites through the metal cation.By controlling the reaction temperature and the reaction time as well asthe composition of the reaction mixture, the metal nanowire having alarge diameter and a large aspect ratio and including the wire portionhaving the at least one bent portion is synthesized. According toreaction conditions, the diameter, the length, and properties relatedthe bent portion of the synthesized metal nanowire can be controlled.

The reaction temperature of the step of synthesizing the metal nanowiremay in a range of 110 to 150° C. When the reaction temperature is below110° C., the time for synthesizing the metal nanowire may increase, anoutput may decreases. When the reaction temperature is above 150° C.,the metal nanowire may be aggregated by an increase of the rapidreaction velocity.

The reaction time of the step of synthesizing the metal nanowire may bein a range of 3 to 12 hours. When the reaction time is below 3, thegrown time of the nanowire may be not sufficient and the length may besmall. When the reaction time is above 12, the nanowires may beaggregated by an overproduction.

In the step of synthesizing the metal nanowire, all materials of areaction mixture are added to a reaction container and a synthesizedreaction is performed at a pressure of an atmospheric pressure or apressure high than the atmospheric pressure to synthesize the metalnanowire. By using an increased pressure, an evaporation pointincreases, and thus, the volatilization of the reaction solution can beminimized and a composition of the reaction solution can be maintained.Accordingly, the length of the metal nanowire according to theembodiment is 1.5 times or more the conventional metal nanowire. Forincreasing the pressure, the reaction container may be sealed, or aninert gas may be injected in the reaction container.

If the composition of the reaction mixture is changed when the metalnanowire is synthesized, the length of the synthesized metal nanowiremay be varied. When the reaction is generated in the state that thereaction container is sealed, inflow and outflow of substances can beprevented during the reaction, and the constant composition can bemaintained. Accordingly, the metal nanowires having uniform lengths canbe obtained.

Additives may be added to synthesize the metal nanowire as necessary.For example, a stabilizer such as an antioxidant and so on, adispersant, a viscosity increasing agent or a thickener, and so on maybe further added, however, the embodiment is not limited. For example,so the length of the metal nanowire can be large, HCl or HNO₃ may beincluded in an amount of 0.1 to 1 parts by weight with respect to allcatalysts contained.

The metal nanowire is cooled to a room temperature after the step ofsynthesizing the metal nanowire, and is cleaned by acetone, ethanol, soon, and then, is purified. Accordingly, the metal nanowire having alarge diameter and a large aspect ratio and including wire portionshaving at least one bent portion can be obtained.

When the metal nanowire is manufactured by a manufacturing methodaccording to an embodiment of the invention, the metal nanowire havingdifferent diameters, as well as, the metal nanowire including wireportions having at least one bent portion, can be synthesized.

2) A Method for Manufacturing a Metal Nanowire Having DifferentDiameters

In a method for manufacturing a metal nanowire having differentdiameters according to an embodiment of the invention, all materials ofa reaction mixture are added to a reaction container and a synthesizedreaction is performed at a pressure of an atmospheric pressure or apressure higher than the atmospheric pressure (for example, 1 to 5 atm)to manufacture the metal nanowire having different diameters bycontrolling an amount of a capping agent in the reaction compound and areaction time.

The manufacturing method according to an embodiment of the invention isfor manufacturing the metal nanowire having at least two wire portionsor wire parts. The metal nanowire includes an n-th wire portion or partand an (n+1) wire portion or part connected to the n-th wire portion orpart. According to the manufacturing method, the metal nanowire havingthe n-th wire portion or part of the n-th diameter and the (n+1)-th wireportion or part of the (n+1)-th diameter of can be synthesized. Bycontrolling elements preventing the surface growth of the metalnanowire, the metal nanowire having different diameters can besynthesized.

The manufacturing method according to the embodiment of the inventioncan synthesize a metal nanowire having a diameter of 50 to 200 nm and alength of 40 to 300 μm. The metal nanowire is grown to be bent, not tobe broken, even the stress above a predetermined value is applied to themetal nanowire when the metal nanowire is synthesized. And thus, themetal nanowire having different diameters can be manufactured.

In addition, the method is an one-pot synthesis. In the one-potsynthesis, a purification of intermediate products is not necessary, andthe metal nanowire having different diameters can be manufactured with ahigh yield without by-products other than the metal nanowire.

More particularly, the method for manufacturing the metal nanowire mayinclude a step S11 of preparing a reaction mixture and a step S21 ofsynthesizing a metal nanowire. In the step S11 of preparing the reactionmixture, the reaction mixture including a metal salt, a capping agent, areducing solvent, and a catalyst are prepared. In the step S21 ofsynthesizing the metal nanowire, the metal nanowire is grown by addingthe reaction mixture to a reaction container and reacting with thereaction mixture in the reaction container. By controlling a compositionand an amount of the reaction mixture, a reaction temperature, areaction pressure, a reaction time, and so on, the metal nanowire havingdifferent diameters with a large diameter and a large aspect ratio canbe synthesized.

In the step S11 of preparing the reaction mixture, the reaction mixtureis prepared by adding the metal salt, the capping agent, the reducingsolvent, and the catalyst to the reaction container with a predeterminedratio and mixing them in the reaction container at a room temperature.The reducing solvent reduces the metal salt to a metal. The cappingagent grows the reduced metal to have a wire shape.

The metal salt is a compound consisting of metal cation and organic orinorganic anion. For example, the metal cation may be a cation of ametal of Ni, Co, Fe, Pt, Au, Ag, Al, Cr, Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti,W, U, V, Zr, Ge, and so on. The organic or inorganic anion may be[NO₃]⁻, [ClO₄]⁻, [BR₄]⁻, [PF₆]⁻, [CH₃COO]⁻, [CF₃SO₃]⁻, [SO₄]²⁻,[CH3COCH═COCH3]⁻, and so on. Two or more metal salts having similarionization degrees may be mixed and the mixed metal salts may be used.Preferably, a silver salt consisting of cation of silver (Ag⁺) and theorganic or inorganic anion may be used.

The metal salt is dissolved by the reducing solvent, and is decomposedto the metal cation and the organic or inorganic anion. The decomposedmetal cation is reduced, and then, is crystallized or grown to the metalnanowire.

A molar concentration of the metal salt is 0.03 mol/l to 0.4 mol/l. Whenthe molar concentration is below 0.03 mol/l, an output of generatedmetal nanowire rapidly decreases. When the molar concentration is above0.4 mol/l, the wires may be aggregated by an overproduction. Morepreferably, the molar concentration of the metal salt may be 0.05 mol/lto 0.10 mol/l.

The reducing solvent may be a polar solvent being able to dissolve themetal salt, the catalyst, and the capping agent. The reducing solventhas at least two hydroxyl groups in molecule. For example, a solventsuch as a diol, a polyol, a glycol, or so on may be used. The reducingsolvent acts as a reducing agent, and reduces the metal salt and forms ametal. As an example, at least one of ethyleneglycol, propyleneglycol,and glycerol may be used, More particularly, at least one ofethyleneglycol, 1, 2-propyleneglycol, 1, 3-propyleneglycol, glycerin,glycerol and diethylglycol may be used.

The capping agent is a chemical agent firstly interacting with sidesurfaces of the grown nanowire and being attached to the side surfacesof the grown nanowire so that a surface of a horizontal cross section ofthe nanowire can be crystallized. That is, the capping agent interactswith the side surface stronger than the surface of the horizontal crosssection. Thus, the side surfaces are passivated, while the surface ofthe horizontal cross section is additionally crystallized to produce thenanowire.

For the capping agent, a surface-attached polymer such aspolyvinylpyrrolidone (PVP), polyvinylalcohol (PVA), polyacrylamide(PAM), polyacrylicacid (PAA), and so on may be used.

The capping agent is included in an amount of 0.05 to 1.0 parts byweight with respect to 28 parts by weight of the reducing solvent. Whenthe capping agent is included below 0.05 parts by weight, the diameterof the metal nanowire may increase. When the capping agent is includedabove 1.0 parts by weight, the length of the metal nanowire may largelydecrease. The capping agent may be included by 0.05 to 0.5 parts byweight with respect to 28 parts by weight of the reducing solvent.

The catalyst is a salt additive including a cation and an anion bondedto each other through an ionic bond. The catalyst is separated to ionsin the polar solvent such as water, an alcohol, a diol, and a polyol. Inthis instance, a cation may be an organic material or an inorganicmaterial, and an anion may be generally an inorganic material and has ahalogen ion (Cl⁻, Br⁻, F⁻, or so on). Anisotropy nano structures arefirstly grown by the catalyst, thereby obtaining the nanowire with arelatively high yield.

The catalyst may include at least one of a compound where a cation andan anion bonded to each other through an ionic bond and a hydratethereof. The cation may be a cation of Al, NH₄, Sb, As, Ba, Bi, Cd, Ca,Cr, Co, Cu, Fe, H, Pb, Mg, Hg, Ni, K, Ag, Na, Sr, and/or Zn. The anionmay be an anion of C₂H₃O₂, Br, CO₃, Cl, CrO₄, OH, I, NO₃, O, C₂O₄, PO₄,SIO₃, SO₄, S, and/or SO₃.

A molar concentration of the catalyst may be in a range of 10⁻⁵ mol/l to10⁻² mol/l. When the molar concentration is below 10⁻⁵ mol/l, thegeneration of the metal nanowire may be declined by a reduction of aninitial nucleation. When the molar concentration is above 10⁻² mol/l, amacro-aggregation may be induced or the surplus catalyst prevents ananisotropic growth of the metal nanowire, the diameter increases, and ageneration of spherical particles may increase.

In the step S21 of synthesizing the metal nanowire, the preparedreaction mixture is reacted in the reaction container. Then, the crystalgrows to the metal nanowire through reducing the metal cation andgrowing crystals from metal nucleation sites through the metal cation.By controlling the reaction temperature and the reaction time as well asthe composition of the reaction mixture, the metal nanowire havingdifferent diameters with a large diameter and a large aspect ratio issynthesized. According to reaction conditions, the diameter, the length,and properties related the different diameters of the synthesized metalnanowire can be controlled.

The reaction temperature of the step of synthesizing the metal nanowiremay in a range of 110 to 150° C. When the reaction temperature is below110° C., the time for synthesizing the metal nanowire may increase, anoutput may decreases. When the reaction temperature is above 150° C.,the metal nanowire may be aggregated by an increase of the rapidreaction velocity.

The reaction time of the step of synthesizing the metal nanowire may bein a range of 3 to 12 hours. When the reaction time is below 3, thegrown time of the nanowire may be not sufficient and the length may besmall. When the reaction time is above 12, the nanowires may beaggregated by an overproduction.

In the step of synthesizing the metal nanowire, all materials of areaction mixture are added to a reaction container and a synthesizedreaction is performed at a pressure of an atmospheric pressure or apressure high than the atmospheric pressure to synthesize the metalnanowire. By using an increased pressure, an evaporation pointincreases, and thus, the volatilization of the reaction solution can beminimized and a composition of the reaction solution can be maintained.Accordingly, the length of the metal nanowire according to theembodiment is 1.5 times or more the conventional metal nanowire. Forincreasing the pressure, the reaction container may be sealed, or aninert gas may be injected in the reaction container.

If the composition of the reaction mixture is changed when the metalnanowire is synthesized, the length of the synthesized metal nanowiremay be varied. When the reaction is generated in the state that thereaction container is sealed, inflow and outflow of substances can beprevented during the reaction, and the constant composition can bemaintained. Accordingly, the metal nanowires having uniform lengths canbe obtained.

Additives may be added to synthesize the metal nanowire as necessary.For example, a stabilizer such as an antioxidant and so on, adispersant, a viscosity increasing agent or a thickener, and so on maybe further added, however, the embodiment is not limited. For example,so the length of the metal nanowire can be large, HCl or HNO₃ may beincluded in an amount of 0.1 to 1 parts by weight with respect to allcatalysts contained.

The metal nanowire is cooled to a room temperature after the step ofsynthesizing the metal nanowire, and is cleaned by acetone, ethanol, soon, and then, is purified. Accordingly, the metal nanowire havingdifferent diameters with a large diameter and a large aspect ratio canbe obtained.

By decreasing the amount of the capping agent and increasing thereaction time compared with the conventional polyol synthesizing method,the capping agent for preventing a growth of side-surfaces of the metalnanowire is sufficient and the first wire portion or part having thefirst diameter is formed in the beginning of the synthesizing reaction.And then, the growth from the first wire portion or part is continuouslygenerated. Then, in the end of the synthesizing reaction, the amount ofthe capping agent decrease and the growth of the side-surfaces of themetal nanowire increases, and therefore, a diameter of the metalnanowire increases and thus the second wire portion or part having thesecond diameter is formed. Accordingly, the metal nanowire including thefirst wire portion or part and a second wire portion or part extendedfrom the first wire portion or part can be synthesized.

When the metal nanowire is manufactured by a manufacturing methodaccording to an embodiment of the invention, the metal nanowireincluding wire portions having at least one bent portion, as well as themetal nanowire having different diameters, can be synthesized.

3) A Method for Manufacturing a Core-Shell Nanowire Having a MetalCoating

A method for manufacturing a core-shell nanowire having a metal-compoundshell according to an embodiment of the invention includes a step ofpreparing a nanowire core on a substrate, a step of contacting thenanowire core with a precursor solution for forming a metal-compoundshell, and a step of forming a metal-compound shell on the nanowire coreby providing growth energy. An absorption ratio of the growth energy tothe nanowire core is higher than an absorption ratio of the growthenergy to the substrate. After the step of forming the metal-compoundshell, a step of cleaning and nitrogen-drying may be further performed.

First, a nanowire core is prepared on a substrate. The nanowire core maybe formed by directly growing the nanowire core on the substrate.Selectively, the metal nanowire may prepared by coating the metalnanowire synthesized by the manufacturing method according to theembodiment of the invention on the substrate. The substrate is notlimited. For example, the substrate may be a transparent substrate.Also, the substrate may be a substrate providing with an additionallayer such as a conductive file or a conductive pattern.

Next, the nanowire core is contacted with a precursor solution forforming the metal-compound shell. The contacting methods may be varied.For example, the precursor solution may be coated on with the nanowirecore on the substrate. Then, the precursor solution may be uniformly andsufficiently contacted to the nanowire core.

The precursor solution may be distilled water. However, the embodimentis not limited thereto. The precursor solution includes a metal organiccompound or its derivatives that is a precursor of the metal compound.The molar concentration of the metal organic compound included in theprecursor solution may be in a range of 0.0001 mol/l to 1 mol/l.However, the embodiment is not limited thereto. When the molarconcentration of the metal organic compound is below 0.0001 mol/l, theprotruded structures may be not sufficient. When the molar concentrationof the metal organic compound is above 1 mol/l, the metal compound maybe unnecessarily coated on the substrate.

The precursor solution may further include a growth accelerating agent.A material of the growth accelerating agent is not limited. Preferably,a basic compound or an amine-based compound may be selected. Forexample, sodium hydroxide, potassium hydroxide, ammonia water,diphenylamine, D-Alanine, D-cysteine, monoethanolamine,monoethylenediamine, S-beta-phenylalanine, chlorophenylamine, and so onmay be used. The molar concentration of the growth accelerating agentmay be 0.0001 mol/l to 1 mol/l per 1 mol of the metal organic compoundincluded in the precursor solution. When the molar concentration of thegrowth accelerating agent is below 0.0001 mol/l, the growth velocity islow. The molar concentration of the growth accelerating agent is above 1mol/l, the protruded structures may be not sufficient or not compete,and the metal compound may be unnecessarily coated on the substrate.

Next, the metal-compound shell is coated on the nanowire core byproviding growth energy. The metal-compound shell is formed by areduction of a metal organic salt through the growth energy. Anabsorption ratio of the growth energy to the nanowire core is higherthan an absorption ratio of the growth energy to the substrate may beselected in order to suppress the formation of the metal compound on thesubstrate. For example, the growth energy is an electromagnetic waveincluding at least one of ultraviolet rays, visible rays, and infraredrays. Preferably, a xenon lamp, a halogen lamp, an ultraviolet (UV)lamp, a laser lamp, and an infrared lamp may be used. By using the xenonlamp, xenon light of a range of 50 W to 1000 W may be irradiated.However, the light having an electric power larger than the range may beused according to a manufacturing area.

Selectively, energy inducing molecular vibrations may be used.Preferably, microwave energy may be used. The energy of the microwaveenergy may be in a range of 50 to 200 W. However, the energy larger thanthe range may be used according to a manufacturing area.

The time of supplying the growth energy is not limited. The time ofsupplying the growth energy may be in a range of 10 seconds to 5minutes. However, the time longer than the range may be possibleaccording to a manufacturing area.

Next, the cleaning and nitrogen-drying may be performed after themetal-compound shell is formed. Alcohol such as ethanol and so on may beused for the cleaning, and nitrogen may be used for the nitrogen-drying.However, the embodiment is not limited thereto.

Meanwhile, the nanowire core including the metal-compound shell may bemanufactured without the substrate. That is, the nanowire core includingthe metal-compound shell can be obtained by a step of preparing ananowire core, a step of contacting the nanowire core with a precursorsolution for forming a metal-compound shell, and a step of forming ametal-compound shell on the nanowire core by providing growth energybeing absorbed to the nanowire core. After the step of forming themetal-compound shell, a step of cleaning and nitrogen-drying may befurther performed. In the step of contacting the nanowire core with aprecursor solution, the nanowire core may be immersed or dipped into aprecursor solution filled in an reaction container.

On the other hand, as shown in FIG. 14, the nanowire core including themetal-compound shell is formed by a roll-to-roll continuous process. Forexample, a flexible substrate is transferred by using rollers 30. Thenanowire core is firstly formed on the substrate by using a nanowiresprayer 40. And then, the flexible substrate with the nanowire corepasses through a dryer 50 and is dried. And then, the precursor solutionfor forming the metal-compound shell is coated through using a coater 60so that the precursor can be sufficiently contacted with the nanowirecore. And then, the metal-compound shell is coated on the nanowire coreby supplying the growth energy through an energy irradiator 70 forapplying growth energy. And then, the cleaning and drying is performedby a cleaning and drying apparatus 80, and thus, the substrate coatedwith the core-shell nanowire including the metal-compound shell can befinally manufactured by the roll-to-roll process.

(3) A Transparent Electrode and an Organic Light Emitting Diode

A transparent electrode and an organic light emitting diode using themetal nanowire or the core-shell nanowire according to an embodiment ofthe invention are provided. It will be understood that when one elementsuch as a layer, a film, a region or a plate is referred to as being“on” another element, the one element may be directly on the anotherelement, and one or more intervening elements may also be present.

The transparent electrode according to the embodiment of the inventionincludes a conductor layer provided on a transparent substrate and atransparent electrode layer formed on the conductor layer. The conductorlayer may include a metal (or core-shell) nanowire according to theembodiment of the invention and metal particles or metal oxideparticles.

For the nanowire included in the conductor layer, the metal (orcore-shell) nanowire having the above properties, that is, the metal (orcore-shell) nanowire having at least one of bent portion, the metal (orcore-shell) nanowire having different diameters, and the core-shellnanowire having the metal coating may be used. The metal (or core-shell)nanowire manufactured by the above-mentioned manufacturing methods maybe used.

The metal particle or the metal oxide included in the conductor layerhas one or more of conductive materials. For example, the metal particleor the metal oxide particle may include at one selected from a groupconsisting of silver (Ag), gold (Au), copper (Cu), platinum (Pt), iron(Fe), nickel (Ni), cobalt (Co), zinc (Zn), titanium (Ti), chrome (Cr),aluminum (Al), palladium (Pd), and oxides thereof. However, theembodiment is not limited.

Preferably, silver (Ag) may be used. The silver (Ag) is a metal, andthus, reflects a light. Also, although the silver has low transmittanceis low, when the silver faces a second electrode (for example, analuminum metal electrode) in the organic light emitting diode, and thelight can be reflected between the silver and the second electrode, andthus, the light loss can be reduced inside the organic light emittingdiode.

The transparent substrate may be formed of a material or a mixtureincluding the material. The material may be selected from a groupconsisting of polyester-based resins including aspolyethyleneterephthalate (PET), polybuthyleneterephthalate (PBT),polyarylate, polysulfone-based resins including polysulfone andpolyethersulfone (PES), polyetherketone-based resins includingpolyetherketone (PEK) and polyetheretherketone (PEEK),polycarbonate-based resins, polyolefin acrylic resins, styrene-basedresins, cellulose derivatives including cellulose triacetate (TAC), andcopolymers thereof.

Also, a transparent substrate may be a silicon substrate, a SOI(SiliconOn Insulator) substrate, a gallium arsenide(GaAs) substrate, a silicongermanium(SiGe) substrate, a ceramic substrate, a quartz substrate, or aglass substrate for lighting. The substrate used for lighting may beunlimitedly used.

One or more of various transparent and conductive materials may be usedfor the transparent electrode layer. Preferably, one or more or metaloxides including ITO(indium tin oxide), ATO(antimony tin oxide),IZO(indium zinc oxide), AZO(ZnO—Al₂O₃, aluminum-doped zinc oxide),GZO(ZnO—Ga₂O₃, Gallium-doped zinc oxide) and graphene, which has a hightransmittance, a high conductivity, and a high heat resistance, may beused for the transparent electrode layer.

The transparent electrode layer may be evenly formed on the conductorlayer or formed on the conductor layer with a curve. In the case thatthe transparent electrode layer is formed with the curve, when a periodof the curvature is Rλa and a height of the curvature is Ra, a ratio ofRa/Rλa (that is, a ratio of the height Ra of the curvature with respectto the period Rλa of the curvature) may be 10⁻³ or more. The transparentelectrode layer can increase the light-scattering effect, and canprotect the nanowire, and the metal particle or the metal oxideparticle.

Also, the organic light emitting diode according to the embodimentincludes a first electrode, a second electrode, and an organic lightemitting layer between the first electrode and the second electrode.

The first electrode may be a transparent electrode including the metal(or core-shell) nanowire with a large diameter and a large aspect ratioaccording to embodiments.

The organic light emitting layer is provided between the first electrodeand the second electrode, and emits the light by an electric drivebetween the first electrode and the second electrode. The organic lightemitting layer has a stacked structure including a light emitting layerand further including at least one selected from a hole injection layer,a hole transfer layer, an electrode transfer layer, and an electrodeinjection layer. A material of the light emitting layer being able toemit light of a visible light range by receiving holes supplied from thehole transfer layer and electrons supplied from the electron transferlayer combining the holes and the electrodes may be used. A materialhaving high quantum efficiency to a fluorescence material or aphosphorescent material may be preferable.

The second electrode is a reflective electrode. The second electrode maybe formed of one or more of an alkali metal, an alkali earth metal, andmetals of groups 3 of the periodic table of the elements. That is, thesecond electrode may be formed of silver (Ag), magnesium (Mg), aluminum,(Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium(Nd), iridium (Ir), chrome (Cr), lithium (Li) or calcium (Ca), or analloy thereof. However, the invention is not limited thereto.

Also, according to an embodiment, an organic light emitting deviceincludes the organic light emitting diode and a sealing substrate. Theorganic light emitting diode includes the transparent substrate, thefirst electrode according to the embodiment, the second electrode facingthe first electrode, and the organic light emitting layer providedbetween the first electrode and the second electrode.

The sealing substrate is provided on the second electrode to cover theorganic light emitting diode on the organic light emitting diode. Thesealing substrate prevents oxygen and water from penetrating through theorganic light emitting diode and protects the organic light emittingdiode.

In the organic light emitting diode used for lighting, inner lightextraction efficiency is very important. The transparent electrodeaccording to the embodiment includes the metal (or core-shell) thenanowire according to the embodiment, and thus, the electricconductivity can increase, and the transmittance and the haze aresuperior. Also, a loss that may be induced by a total reflection of thelight generated in the organic light emitting diode due to thereflective index can be reduced, and scattering is induced. Accordingly,the organic light emitting diode and the organic light emitting diodecan have the enhanced inner light extraction effect.

For example, the transparent electrode has a sheet resistance of 50Ω/□or less.

Advantageous Effects

A metal nanowire according to the invention has a large diameter and alarge aspect ratio and includes a plurality of wire portions having atleast one bent portion. Thus, contact points, contact areas, or acontact probability between the metal nanowires can increase, a sheetresistance can be relatively low, an electric conductivity can besuperior, and a light-scattering effect can be achieved.

Also, a metal nanowire according to the invention has a large diameterand a large aspect ratio and having different diameters. Thus, contactpoints, contact areas, or a contact probability between the metalnanowires can increase, a sheet resistance can be relatively low, anelectric conductivity can be superior, and a light-scattering effect canbe achieved.

In addition, a core-shell nanowire according to the invention has ametal coating. A sulfidation and an oxidation can be prevented andreliability can be enhanced. A light-scattering property can beenhanced, and a high haze can be achieved without largely reducing anelectric conductivity and a transmittance.

Furthermore, a method for manufacturing a metal nanowire according theinvention is an one-pot synthesis. In the method for manufacturing themetal nanowire, a purification of intermediate products is notnecessary, and the metal nanowire can be manufactured with a high yieldwithout by-products other than the metal nanowire.

Also, in a method for manufacturing a metal nanowire according to theinvention, volatilization of a reaction mixture can be minimized byadding all of a reaction mixture to a reaction container and reactingwith the reaction mixture at a pressure of an atmospheric pressure or apressure high than the atmospheric pressure. The metal nanowire can begrown to be bent, not to be broken, even the metal nanowire has a largediameter and a large aspect ratio. Thus, the metal nanowire including aplurality of wire portions having at least one bent portion can bemanufactured.

Further, in a method for manufacturing a metal nanowire according to theinvention, a side-surface growth of the metal nanowire can be controlledby controlling an amount of a capping agent, and the metal nanowirehaving different diameters can be manufactured.

In addition, a method for manufacturing a core-shell nanowire accordingto the invention can be applied to a metal nanowire including aplurality of wire portions having at least one bent portion and a metalnanowire having different diameters, as well as the known, marketed, orgenerally used metal nanowire. Thus, a core-shell nanowire having ametal-compound shell can be manufactured.

Furthermore, according to a method for manufacturing a transparentelectrode and an organic light emitting diode including a metal nanowirehaving a large diameter and a large aspect ratio and including aplurality of wire portions having at least one bent portion as aconductor layer, the transparent electrode having a transmittance and ahaze suitable for an OLED lighting or an organic solar cell at a rangeof visibly ray can be manufactured.

Also, according to a method for manufacturing a transparent electrodeand an organic light emitting diode including a metal nanowire having alarge diameter and a large aspect ratio and having different diametersas a conductor layer, the transparent electrode having a transmittanceand a haze suitable for an OLED lighting or an organic solar cell at arange of visibly ray can be manufactured.

Furthermore, according to a method for manufacturing a transparentelectrode and an organic light emitting diode including a core-shellnanowire having a metal coating, a sulfidation and an oxidation can beprevented and reliability can be enhanced. A light-scattering propertycan be enhanced, and a high haze can be achieved without largelyreducing an electric conductivity and a transmittance.

Embodiment 1) Embodiment 1 to Embodiment 10—A Metal Nanowire Including aPlurality of Wire Portions Having at Least One Bent Portion Embodiment 1

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 1 atm and130° C. for 5 hours, thereby obtaining silver nanowires including wireportions having at least one bent portion.

Embodiment 2

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 3 atm and130° C. for 5 hours, thereby obtaining silver nanowires including wireportions having at least one bent portion.

Embodiment 3

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 5 atm and130° C. for 5 hours, thereby obtaining silver nanowires including wireportions having at least one bent portion.

Embodiment 4

Silver nanowires including wire portions having at least one bentportion were obtained by the same method according to Embodiment 2,except that the molar concentration of FeCl₃ was 5×10⁻³ mol/l and thereaction time is 1 hour.

Embodiment 5

Silver nanowires having wire portion having at least one bent portionwere obtained by the same method according to Embodiment 2, except thatthe molar concentration of FeCl₃ was 5×10⁻³ mol/l and the reaction timeis 6 hours.

Embodiment 6

Silver nanowires including wire portions having at least one bentportion were obtained by the same method according to Embodiment 2,except that the molar concentration of FeCl₃ was 5×10⁻³ mol/l and thereaction time is 12 hours.

Embodiment 7

Silver nanowires having at least one bent portion and having differentdiameters were obtained by the same method according to Embodiment 2,except that the reaction temperature was 110° C.

Embodiment 8

Silver nanowires having at least one bent portion and having differentdiameters were obtained by the same method according to Embodiment 2,except that the reaction temperature was 150° C.

Embodiment 9

Silver nanowires having at least one bent portion and having differentdiameters were obtained by the same method according to Embodiment 2,except that an amount of the PVP(Mw ˜360,000) was 0.8 g.

Embodiment 10

Silver nanowires having at least one bent portion and having differentdiameters were obtained by the same method according to Embodiment 2,except that an amount of the PVP(Mw ˜360,000) was 1.5 g.

2) Embodiment 11 to Embodiment 22—a Metal Nanowire Including HavingDifferent Diameters Embodiment 11

A reaction mixture was prepared by mixing 0.2 mol/l of AgNO₃, 28 g ofEG(99.5%), 0.1 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 1 atm and130° C. for 3 hours, thereby obtaining silver nanowires having differentdiameters.

Embodiment 12

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 11, except thatreaction time is 4 hours.

Embodiment 13

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 11, except thatreaction time is 5 hours.

Embodiment 14

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 11, except thatreaction time is 6 hours.

Embodiment 15

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 11, except thatreaction time is 7 hours.

Embodiment 16

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 0.05 g of PVP(Mw ˜360,000), and 5×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 3 atm and130° C. for 3 hours, thereby obtaining silver nanowires having differentdiameters.

Embodiment 17

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 11, except thatreaction time is 4 hours.

Embodiment 18

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 16, except thatreaction time is 5 hours.

Embodiment 19

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 16, except thatreaction time is 6 hours.

Embodiment 20

Silver nanowires including wire portions having different diameters wereobtained by the same method according to Embodiment 16, except thatreaction time is 7 hours.

Embodiment 21

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 0.1 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 3 atm and110° C. for 12 hours, thereby obtaining silver nanowires havingdifferent diameters and having at least one bent portion.

Embodiment 22

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 0.05 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 3 atm and150° C. for 12 hours, thereby obtaining silver nanowires havingdifferent diameters and having at least one bent portion.

3) Comparative Example 1 to Comparative Example 7 Comparative Example 1

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was not sealed, and then, a reaction was generated at 1 atmand 130° C. for 5 hours, thereby obtaining silver nanowires.

Comparative Example 2

A reaction mixture was prepared by mixing 0.15 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was not sealed, and then, a reaction was generated at 1 atmand 130° C. for 5 hours, thereby obtaining silver nanowires.

Comparative Example 3

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻⁵ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was not sealed, and then, a reaction was generated at 3 atmand 130° C. for 5 hours, thereby obtaining silver nanowires.

Comparative Example 4

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 5×10⁻⁵ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was not sealed, and then, a reaction was generated at 3 atmand 130° C. for 5 hours, thereby obtaining silver nanowires.

Comparative Example 5

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 3 g of PVP(Mw ˜360,000), and 1×10⁻⁴ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was not sealed, and then, a reaction was generated at 3 atmand 130° C. for 5 hours, thereby obtaining silver nanowires.

Comparative Example 6

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 0.5 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 3 atm and130° C. for 2 hours, thereby obtaining silver nanowires.

Comparative Example 7

A reaction mixture was prepared by mixing 0.1 mol/l of AgNO₃, 28 g ofEG(99.5%), 1 g of PVP(Mw ˜360,000), and 1×10⁻³ mol/l of FeCl₃. Thereaction mixture was added into a single container and the singlecontainer was sealed, and then, a reaction was generated at 3 atm and130° C. for 1 hour, thereby obtaining silver nanowires.

TABLE 1 amount or concentration of Reaction conditions of Seal Preparinga reaction mixture Synthesizing silver nanowires [◯] M.S R.S C.A C P TTemp or not-seal [mol/l] [g] [g] [mol/l] [atm] [hr] [° C.] [X]Embodiment 1 0.1 28 3 1 × 10⁻³ 1 5 130 ◯ Embodiment 2 0.1 28 3 1 × 10⁻³3 5 130 ◯ Embodiment 3 0.1 28 3 1 × 10⁻³ 5 5 130 ◯ Embodiment 4 0.1 28 35 × 10⁻³ 3 1 130 ◯ Embodiment 5 0.1 28 3 5 × 10⁻³ 3 6 130 ◯ Embodiment 60.1 28 3 5 × 10⁻³ 3 12 130 ◯ Embodiment 7 0.1 28 3 1 × 10⁻³ 3 5 110 ◯Embodiment 8 0.1 28 3 1 × 10⁻³ 3 5 150 ◯ Embodiment 9 0.1 28 0.8 1 ×10⁻³ 3 5 130 ◯ Embodiment 10 0.1 28 1.5 1 × 10⁻³ 3 5 130 ◯ Embodiment 110.2 28 0.1 1 × 10⁻³ 1 3 130 ◯ Embodiment 12 0.2 28 0.1 1 × 10⁻³ 1 4 130◯ Embodiment 13 0.2 28 0.1 1 × 10⁻³ 1 5 130 ◯ Embodiment 14 0.2 28 0.1 1× 10⁻³ 1 6 130 ◯ Embodiment 15 0.2 28 0.1 1 × 10⁻³ 1 7 130 ◯ Embodiment16 0.1 28 0.05 5 × 10⁻³ 3 3 130 ◯ Embodiment 17 0.1 28 0.05 5 × 10⁻³ 3 4130 ◯ Embodiment 18 0.1 28 0.05 5 × 10⁻³ 3 5 130 ◯ Embodiment 19 0.1 280.05 5 × 10⁻³ 3 6 130 ◯ Embodiment 20 0.1 28 0.05 5 × 10⁻³ 3 7 130 ◯Embodiment 21 0.1 28 0.1 1 × 10⁻³ 3 12 110 ◯ Embodiment 22 0.1 28 0.05 1× 10⁻³ 3 12 150 ◯ Comparative 0.1 28 3 1 × 10⁻³ 1 5 130 X Example 1Comparative 0.15 28 3 1 × 10⁻³ 1 5 130 X Example 2 Comparative 0.1 28 31 × 10⁻⁵ 3 5 130 X Example 3 Comparative 0.1 28 3 5 × 10⁻⁵ 3 5 130 XExample 4 Comparative 0.1 28 3 1 × 10⁻⁴ 3 5 130 X Example 5 Comparative0.1 28 0.5 1 × 10⁻³ 3 2 130 ◯ Example 6 Comparative 0.1 28 1 1 × 10⁻³ 31 130 ◯ Example 7 [M.S: a metal salt, R.S: a reducing solution, C.A: acapping agent, C: catalyst, P: pressure, T: time, Temp: Temperature]

4) Embodiment 23 to Embodiment 32—A Core-Shell Nanowire Having a MetalCoating Embodiment 23

0.001 mol/l of zinc acetate dehydrate and 0.001 mol/lhexamethylenedimaine were added to distilled water to prepare aprecursor solution. And then, the precursor solution was coated on asubstrate coated with silver nanowires. And then, light was irradiatedto the substrate by using a white light source for 5 minutes. After thecompletion of the reaction, the substrate was washed by using ethanoland was dried by using nitrogen, and thus, the core-shell nanowires weremanufactured.

Embodiment 24

Core-shell nanowires were manufactured by the same method according toEmbodiment 23, except that the molar concentration of the zinc acetatedehydrate was 0.01 mol/l and the amount of the hexamethylenediamine was0.01 mol/l.

Embodiment 25

Core-shell nanowires were manufactured by the same method according toEmbodiment 23, except that the molar concentration of the zinc acetatedehydrate was 0.10 mol/l and the amount of the hexamethylenediamine was0.10 mol/l.

Embodiment 26

Core-shell nanowires were manufactured by the same method according toEmbodiment 23, except that the molar concentration of the zinc acetatedehydrate was 0.50 mol/l and the amount of the hexamethylenediamine was0.50 mol/l.

Embodiment 27

Core-shell nanowires were manufactured by the same method according toEmbodiment 23, except that the molar concentration of the zinc acetatedehydrate was 1.00 mol/l and the amount of the hexamethylenediamine was1.00 mol/l.

Embodiment 28

0.001 mol/l of zinc nitrate and 0.001 mol/l hexamethylenedimaine wereadded to distilled water to prepare a precursor solution. And then, theprecursor solution was coated on a substrate coated with the silvernanowires. And then, microwave of 1000 W is applied for 30 seconds.After the completion of the reaction, the substrate was washed by usingethanol and was dried by using nitrogen, and thus, the core-shellnanowires were manufactured.

Embodiment 29

Core-shell nanowires were manufactured by the same method according toEmbodiment 28, except that the molar concentration of the zinc nitratewas 0.01 mol/l and the amount of the hexamethylenediamine was 0.01mol/l.

Embodiment 30

Core-shell nanowires were manufactured by the same method according toEmbodiment 28, except that the molar concentration of the zinc nitratewas 0.10 mol/l and the amount of the hexamethylenediamine was 0.10mol/l.

Embodiment 31

Core-shell nanowires were manufactured by the same method according toEmbodiment 28, except that the molar concentration of the zinc nitratewas 0.50 mol/l and the amount of the hexamethylenediamine was 0.50mol/l.

Embodiment 32

Core-shell nanowires were manufactured by the same method according toEmbodiment 28, except that the molar concentration of the zinc nitratewas 1.00 mol/l and the amount of the hexamethylenediamine was 1.00mol/l.

Comparative Example 8 to Comparative Example 12

The substrates coated with the silver nanowires according Embodiment 23to Embodiment 27 before a zinc oxide coating, which were not coated witha zinc oxide, were used as the Comparative Example 8 to ComparativeExample 12, respectively.

Comparative Example 13 to Comparative Example 17

The substrates coated with the silver nanowires according Embodiment 28to Embodiment 32 before a zinc oxide coating, which were not coated witha zinc oxide, were used as the Comparative Example 13 to ComparativeExample 17, respectively.

Test Example

1) Measuring a Diameter and a Length, and Calculating an Aspect Ratio

The diameters and the lengths of the silver nanowires synthesizedaccording to Embodiments and Comparative Examples were measured, and theaspect ratios were calculated. The result are shown in TABLE 2.

TABLE 2 Length Aspect 1^(st) diameter[nm] 2^(nd)diameter[um]3^(rd)diameter[m] [m] ratio Embodiment 1 80 100 1250 Embodiment 2 100150 1500 Embodiment 3 120 230 1917 Embodiment 4 60 60 1000 Embodiment 5150 120 800 Embodiment 6 200 230 1150 Embodiment 7 90 0.3-0.9 0.2-0.6100 1111 Embodiment 8 150 0.4-1.2 0.4-1.0 130 867 Embodiment 9 200 100500 Embodiment 10 150 100 667 Embodiment 11 50 0.01-0.1  70 1400Embodiment 12 60 0.02-0.13 100 1667 Embodiment 13 80 0.03-0.15 140 1750Embodiment 14 80 0.025-0.2  0.025-0.1  150 1875 Embodiment 15 90 0.1-0.30.1-0.3 160 1778 Embodiment 16 60 0.03-0.1  50 833 Embodiment 17 700.06-0.2  70 1000 Embodiment 18 80 0.1-0.2 0.08-0.15 100 1250 Embodiment19 100 0.15-0.35 0.08-0.2  120 1200 Embodiment 20 130 0.2-0.5 0.1-0.5150 1154 Embodiment 21 90 0.3-0.9 0.2-0.6 100 1111 Embodiment 22 1500.4-1.2 0.4-1.0 130 867 Comparative 60 40 667 Example 1 Comparative 8040 500 Example 2 Comparative 50 15 300 Example 3 Comparative 55 20 364Example 4 Comparative 60 30 500 Example 5 Comparative 150 30 200 Example6 Comparative 100 30 300 Example 7

As shown in TABLE 2, it can be seen that the silver nanowires accordingto Embodiments have diameters and lengths larger than diameters andlengths of the silver nanowires according to Comparative Examples. Also,it can be seen that the aspect ratios of the silver nanowires accordingto Embodiments are generally above 1000.

Also, the silver nanowires according to Embodiment 7, 8 and Embodiment11 to 22 have a plurality of diameters having a second diameter, a thirddiameter, and so on. On the other hand, each of the silver nanowiresaccording to Comparative Examples has a uniform diameter.

2) Analysis of a Scanning Electron Microscopy (SEM)

FIG. 15 is a photograph of a surface of silver nanowires according to anembodiment of the invention, taken using a scanning electron microscopy.As shown in FIG. 15, the manufactured silver nanowires have a diameterdistribution 15 a of D1 (124.47 nm), D2 (81.48 nm), D3 (84.42 nm), D4(85.93 nm), D5 (84.65 nm), D6 (98.13 nm), D7 (134.80 nm), and D8 (67.15nm). That is, the silver nanowires have large diameters. Also, themanufactured silver nanowires have a length distribution 15 b of D1(194.79 μm), D2 (182.86 μm), D3 (100.14 μm), D4 (193.74 μm), D5 (111.31μm), D6 (243.61 μm), D7 (95.14 μm), and D8 (123.00 μm). That is, thesilver wires have large lengths.

FIG. 16 is a photograph of silver nanowires having a plurality of wireparts having different diameters according to an embodiment of theinvention, taken using a scanning electron microscopy. As shown in FIG.16, it can be seen that a second part having the second diameterconnected to a first part having a first diameter is formed.

3) Analysis Using Transmission Electron Microscope (TEM)

FIG. 17 and FIG. 18 are photographs of silver nanowires including aplurality of wire portions having at least one bent portion according toan embodiment of the invention, taken using a transmission electronmicroscopy. The silver nanowires having bent shapes bent to apredetermined direction can be seen. FIG. 19 is a photograph of silvernanowires not including a plurality of wire portions and not having atleast one bent portion as a comparative example, taken using atransmission electron microscopy.

The number of the bent portion an and average angle of the bent portionof the silver nanowires including the plurality of wire portion havingat least one bent portion are shown in TABLE 3.

TABLE 3 1^(st) 2^(nd) 3^(rd) diameter diameter diameter Length A.B [nm][μm] [μm] [μm] N.B [°] Embodiment 1 80 100 2 155 Embodiment 2 100 150 2110 Embodiment 3 120 230 3 87 Embodiment 4 60 60 1 150 Embodiment 5 150120 2 155 Embodiment 6 200 230 2 160 Embodiment 7 90 0.3-0.9 0.2-0.6 1002 150 Embodiment 8 150 0.4-1.2 0.4-1.0 130 2 160 Embodiment 9 200 100 2155 Embodiment 10 150 100 2 155 Embodiment 11 50 0.01-0.1  70 Embodiment12 60 0.02-0.13 100 Embodiment 13 80 0.03-0.15 140 Embodiment 14 800.025-0.2  0.025-0.1  150 Embodiment 15 90 0.1-0.3 0.1-0.3 160Embodiment 16 60 0.03-0.1  50 Embodiment 17 70 0.06-0.2  70 Embodiment18 80 0.1-0.2 0.08-0.15 100 Embodiment 19 100 0.15-0.35 0.08-0.2  120Embodiment 20 130 0.2-0.5 0.1-0.5 150 Embodiment 21 90 0.3-0.9 0.2-0.6100 2 150 Embodiment 22 150 0.4-1.2 0.4-1.0 130 2 160 Comparative 60 40Example 1 Comparative 80 40 Example 2 Comparative 50 15 Example 3Comparative 55 20 Example 4 Comparative 60 30 Example 5 Comparative 15030 Example 6 Comparative 100 30 Example 7 [N.B: the number of the bentportions, A.B: an average angle of the bent portion]

As shown in TABLE 3, it can be seen that the silver nanowires accordingto Embodiments generally include two to three bent portions, while thesilver nanowires according to Comparative Examples do not include thebent portion. Also, it can be seen that the nanowires according toEmbodiments 21 and 22 have different diameters and have at least onebent portion.

Experimental Example 1) Measuring Electric Conductivity (SheetResistance)

A sheet resistance of a transparent substrate including silver nanowiresaccording to each Embodiments and Comparative Examples was measured 15times by using a 4-point probe. An average sheet resistance and astandard deviation were calculated. Also, the average sheet resistanceand the standard deviation are shown in TABLE 4.

TABLE 4 average sheet resistance(Ω/□) Standard deviation Embodiment 1 257.5 Embodiment 2 21 6.3 Embodiment 3 40 12 Embodiment 4 80 24 Embodiment5 82 24.6 Embodiment 6 42 12.6 Embodiment 7 27 8.1 Embodiment 8 37 11.1Embodiment 9 29 8.7 Embodiment 10 42 12.6 Embodiment 11 108 20.4Embodiment 12 97 18.9 Embodiment 13 68 16.7 Embodiment 14 54 13.9Embodiment 15 40 12.2 Embodiment 16 115 31.1 Embodiment 17 110 29.7Embodiment 18 48 7.3 Embodiment 19 43 9.7 Embodiment 20 35 8.3Embodiment 21 27 8.1 Embodiment 22 37 11.1 Comparative 58 17.4 Example 1Comparative 75 22.5 Example 2 Comparative 73 21.9 Example 3 Comparative90 27 Example 4 Comparative 120 36 Example 5 Comparative 160 48 Example6 Comparative 180 54 Example 7

As shown in TABLE 4, the transparent electrodes including the silvernanowires according to Embodiments have sheet resistances of a minimumof 21Ω/□, a maximum of 115Ω/□, and an average of 54.9Ω/□. On the otherhand, the transparent electrodes including the silver nanowiresaccording to Comparative Examples have sheet resistances of a minimum of58Ω/□, a maximum of 180Ω/□, and an average of 108Ω/□. It can be seenthat the silver nanowires according to the invention can prevent thesheet resistance from increasing and thus the transparent electrode canhave a superior electric conductivity.

2) Measuring a Transmittance and a Haze

A transmittance and a haze of a transparent substrate including silvernanowires according to each Embodiments and Comparative Examples weremeasured, and the results are shown in TABLE 5. FIG. 20 is graphs oftransmittances, wherein (a) of FIG. 20 is a graph of transmittances of atransparent substrate including silver nanowires according to each ofEmbodiments 11 to 15, and (b) of FIG. 20 is a graph of transmittances ofa transparent substrate including silver nanowires according to each ofEmbodiments 16 to 20. FIG. 21 is graphs of hazes, wherein (a) of FIG. 21is a graph of a haze of a transparent substrate including silvernanowires according to each of Embodiments 11 to 15, and (b) of FIG. 21is a graph of a haze of each of a transparent substrate including silvernanowires according to Embodiments 16 to 20.

TABLE 5 transmittance(%) haze[%] Embodiment 1 88.3 1.2 Embodiment 2 88.21.5 Embodiment 3 88.6 2.2 Embodiment 4 88.8 1.2 Embodiment 5 88.7 1.8Embodiment 6 88.5 2 Embodiment 7 87.2 10.2 Embodiment 8 87.7 17.4Embodiment 9 88.3 1.2 Embodiment 10 88.2 1.5 Embodiment 11 86.7 4.5Embodiment 12 84 8.4 Embodiment 13 85.9 6.1 Embodiment 14 86.9 4.8Embodiment 15 85.8 6.6 Embodiment 16 85.4 5.9 Embodiment 17 83.2 9.1Embodiment 18 85.5 7.3 Embodiment 19 82.1 11.2 Embodiment 20 84.3 7.4Embodiment 21 87.2 10.2 Embodiment 22 87.7 17.4 Comparative 89.9 1.2Example 1 Comparative 88.7 1.5 Example 2 Comparative 89.3 1.3 Example 3Comparative 89.3 1.4 Example 4 Comparative 88.2 1.7 Example 5Comparative 87.1 2 Example 6 Comparative 87.7 1.6 Example 7

The haze may be below 1% when the transparent electrode is used for adisplay device. On the other hand, when the transparent electrode isused for an OLED lighting (an inner light extraction layer) or anorganic solar cell, the haze of 1% or more (more particularly, 5% ormore) is necessary. As shown in TABLE 5, the transmittances of thetransparent electrodes including the silver nanowires according toEmbodiments are similar to those according to Comparative Examples. Thehazes of the transparent electrodes including the silver nanowiresaccording to some Embodiments are similar to the those according toComparative Examples, and the hazes of the transparent electrodesincluding the silver nanowires according to other Embodiments are high(for example, 10% or more). Thus, the transparent electrode can haveproperties suitable for an OLED lighting (an inner light extractionlayer) or an organic solar cell.

3) Experimental Embodiment of Embodiments 23 to 27 and ComparativeExamples 8 to 12

FIG. 22 and FIG. 23 are scanning electron microscopy photographs ofcore-shell nanowires according to Embodiments 23 to 27. As shown in FIG.22 and FIG. 23, it can be seen that metal-compound shells having aplurality of stripe patterns extending in a longitudinal direction ofthe nanowire are formed.

Also, FIG. 24 is a photograph for illustrating that a zinc oxide isselectively coated on the nanowire formed on a core-shell nanowiresubstrate. As shown in FIG. 24, it can be seen that the zinc oxide isselectively coated only on the nanowire.

FIG. 25 is a graph of sheet resistances of Embodiments. It can be seenthat the sheet resistances of the silver nanowires after the coating aresimilar to the sheet resistances of the silver nanowires before thecoating. Also, in some Embodiments, it can be seen that the sheetresistances of the silver nanowires after the coating of the metal-oxideshell are higher than the sheet resistances of the silver nanowiresbefore the coating of the metal-oxide shell.

Also, FIG. 26 is X-ray diffraction peaks of the core-shell nanowiresaccording to Embodiments. It can be seen that there is a peak of a metaloxide and that an intensity of the peak of the metal oxide increases asa coated amount increases.

In addition, FIG. 27 to FIG. 29 are graphs of light transmittances ofEmbodiment 23 to Embodiment 27. It can be seen that the lighttransmittance can be very superior.

Further, FIG. 30 to FIG. 32 are graphs of hazes of Embodiment 23 toEmbodiment 27. It can be seen that the haze largely increases as thecoated amount of the metal oxide shell.

Also, FIG. 33 is a graph of a photoluminescence (PL) according to eachof Embodiments 23 to 25.

In addition, FIG. 34 is a graph of a sheet resistance with respect totime, according to Embodiment 23 to Embodiment 27. It can be seen thatthe sheet resistance is generally maintained as the time goes.

For example, when the core-shell nanowire is coated on a transparentsubstrate to have a sheet resistance of 1˜100(Ω/□), a haze may be in arange of 5% or more (for example, 20% or more) at a wavelength of 550nm. When the core-shell nanowire is coated on a transparent substrate tohave a sheet resistance of 1˜100(Ω/□), a light transmittance may be in arange of 60 to 98% at a wavelength of 550 nm.

4) An Exemplary Example of Embodiments 28 to 32 and Comparative Examples13 to 17

FIG. 35 and FIG. 36 are scanning electron microscopy photographs ofcore-shell nanowires according to Embodiments 28 to 32. As shown in FIG.35 and FIG. 36, it can be seen that metal-compound shells having aplurality of stripe patterns extending in a longitudinal direction ofthe nanowire are formed.

Also, FIG. 37 is a photograph for illustrating that a zinc oxide isselectively coated on the nanowire formed on a core-shell nanowiresubstrate. As shown in FIG. 37, it can be seen that the zinc oxide isselectively coated only on the nanowire.

FIG. 28 is a graph of sheet resistances of Embodiments of ComparativeExamples. It can be seen that the sheet resistances of the silvernanowires after the coating are similar to the sheet resistances of thesilver nanowires before the coating. Also, in some Embodiments, it canbe seen that the sheet resistances of the silver nanowires after thecoating of the metal-oxide shell are higher than the sheet resistancesof the silver nanowires before the coating of the metal-oxide shell.

Also, FIG. 39 is X-ray diffraction peaks of the core-shell nanowiresaccording to Embodiments. It can be seen that there is a peak of a metaloxide and that an intensity of the peak of the metal oxide increases asa coated amount increases.

Further, FIG. 40 to FIG. 42 are graphs of hazes of Embodiment 28 toEmbodiment 32. It can be seen that the haze largely increases as thecoated amount of the metal oxide shell.

In addition, FIG. 43 to FIG. 45 are graphs of light transmittance ofEmbodiment 28 to Embodiment 32. It can be seen that the lighttransmittance can be very superior.

Also, FIG. 46 is a graph of a photoluminescence (PL) according to eachof Embodiments 28 to 32.

In addition, FIG. 47 is a graph of a sheet resistance with respect totime, according to each of Embodiment 28, 29, and 32. It can be seenthat the sheet resistance is generally maintained as the time goes.

For example, when the core-shell nanowire is coated on a transparentsubstrate to have a sheet resistance of 1˜100(Ω/□), a haze may be in arange of 5% or more (for example, 20% or more) at a wavelength of 550nm. When the core-shell nanowire is coated on a transparent substrate tohave a sheet resistance of 1˜100(Ω/□), a light transmittance may be in arange of 60 to 98% at a wavelength of 550 nm.

The above described features, configurations, effects, and the like areincluded in at least one of the embodiments of the present invention,and should not be limited to only one embodiment. In addition, thefeatures, configurations, effects, and the like as illustrated in eachembodiment may be implemented with regard to other embodiments as theyare combined with one another or modified by those skilled in the art.Thus, content related to these combinations and modifications should beconstrued as including in the scope and spirit of the invention asdisclosed in the accompanying claims.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a metal nanowire including two wire portions having abent portion, according to an embodiment of the invention.

FIG. 2 illustrates a metal nanowire including a plurality of wireportions having at least one bent portion, according to anotherembodiment of the invention.

FIG. 3 illustrates a three-dimensional structure of a metal nanowireincluding a plurality of wire portions having at least one bent portion,according to yet another embodiment of the invention.

FIG. 4 illustrates a metal nanowire including a plurality of wire partshaving different diameters, wherein the plurality of wire partsincluding one second wire part, according to yet still anotherembodiment of the invention.

FIG. 5 illustrates a metal nanowire including a plurality of wire partshaving different diameters according to another embodiment of theinvention, wherein (a) illustrates the metal nanowire including a secondwire part formed at one end and (b) illustrates the metal nanowireincluding second wire parts formed at both ends.

FIG. 6 illustrates wire portions of a metal nanowire having at least onebent portion according to yet still another embodiment of the invention.

FIG. 7 illustrates the metal nanowire having at least one bent portionaccording to yet still another embodiment of the invention.

FIG. 8 illustrates wire parts of a metal nanowire having differentdiameters according to yet still another embodiment of the invention.

FIG. 9 illustrates the metal nanowire having different diametersaccording to yet still another embodiment of the invention.

FIG. 10 to FIG. 13 schematically illustrate core-shell nanowiresaccording to embodiments of the invention.

FIG. 14 a schematically view of a roll-to-roll continuation process forforming a core-shell nanowire according to an embodiment of theinvention.

FIG. 15 is a photograph of a surface of silver nanowires according to anembodiment of the invention, taken using a scanning electron microscopy.

FIG. 16 is a photograph of silver nanowires having a plurality of wireparts having different diameters according to an embodiment of theinvention, taken using a scanning electron microscopy.

FIG. 17 and FIG. 18 are photographs of silver nanowires including aplurality of wire portions having at least one bent portion according toan embodiment of the invention, taken using a transmission electronmicroscopy.

FIG. 19 is a photograph of silver nanowires not including a plurality ofwire portions and not having at least one bent portion as a comparativeexample, taken using a transmission electron microscopy.

FIG. 20 is graphs of transmittances, wherein (a) of FIG. 20 is a graphof a transmittance of a transparent substrate including silver nanowiresaccording to each of Embodiments 11 to 15, and (b) of FIG. 20 is a graphof a transmittance of a transparent substrate including silver nanowiresaccording to each of Embodiments 16 to 20.

FIG. 21 is graphs of hazes, wherein (a) of FIG. 21 is a graph of a hazeof a transparent substrate including silver nanowires according to eachof Embodiments 11 to 15, and (b) of FIG. 21 is a graph of a haze of atransparent substrate including silver nanowires according to each ofEmbodiments 16 to 20.

FIG. 22 and FIG. 23 are scanning electron microscopy photographs ofcore-shell nanowires according to Embodiments 23 to 27, wherein (a) ofFIG. 22 corresponds to Embodiment 23, (b) of FIG. 22 corresponds toEmbodiment 24, (c) of FIG. 23 corresponds to Embodiment 25, (a) of FIG.23 corresponds to Embodiment 26, and (b) of FIG. 23 corresponds toEmbodiment 27.

FIG. 24 is a photograph for illustrating that a zinc oxide isselectively coated on a nanowire formed on a core-shell nanowiresubstrate, according to Embodiment 25.

FIG. 25 is a graph of sheet resistances of each of Embodiments ofComparative Examples.

FIG. 26 is X-ray diffraction peaks of the core-shell nanowires accordingto Embodiments, wherein (a) of FIG. 26 corresponds to Embodiment 23, (b)of FIG. 26 corresponds to Embodiment 24, and (c) of FIG. 26 correspondsto Embodiment 27.

FIG. 27 to FIG. 29 are graphs of light transmittances of Embodiment 23to Embodiment 27, wherein (a) of FIG. 27 corresponds to Embodiment 23,(b) of FIG. 27 corresponds to Embodiment 24, (a) of FIG. 28 correspondsto Embodiment 25, (b) of FIG. 28 corresponds to Embodiment 26, and 29corresponds to Embodiment 27.

FIG. 30 to FIG. 32 are graphs of hazes of Embodiment 23 to Embodiment27, wherein (a) of FIG. 30 corresponds to Embodiment 23, (b) of FIG. 30corresponds to Embodiment 24, (a) of FIG. 31 corresponds to Embodiment25, (b) of FIG. 31 corresponds to Embodiment 26, and FIG. 32 correspondsto Embodiment 27.

FIG. 33 is a graph of a photoluminescence (PL) according to each ofEmbodiments 23 to 25, wherein (a) of FIG. 33 corresponds to Embodiment23, (b) of FIG. 33 corresponds to Embodiment 24, (c) of FIG. 33corresponds to Embodiment 25.

FIG. 34 is a graph of a sheet resistance with respect to time, accordingto each of Embodiment 23 to Embodiment 27.

FIG. 35 and FIG. 36 are scanning electron microscopy photographs ofcore-shell nanowires according to Embodiments 28 to 32, wherein (a) ofFIG. 35 corresponds to Embodiment 28, (b) of FIG. 35 corresponds toEmbodiment 29, (c) of FIG. 35 corresponds to Embodiment 30, (a) of FIG.36 corresponds to Embodiment 31, and (b) of FIG. 36 corresponds toEmbodiment 32.

FIG. 37 is a photograph for illustrating that a zinc oxide isselectively coated on a nanowire formed on a core-shell nanowiresubstrate.

FIG. 38 is a graph of sheet resistances of each of Embodiments ofComparative Examples.

FIG. 39 is X-ray diffraction peaks of the core-shell nanowires accordingto Embodiments, wherein (a) of FIG. 39 corresponds to Embodiment 28, (b)of FIG. 39 corresponds to Embodiment 29, and (c) of FIG. 39 correspondsto Embodiment 32.

FIG. 40 to FIG. 42 are graphs of hazes of Embodiment 28 to Embodiment32, wherein (a) of FIG. 40 corresponds to Embodiment 28, (b) of FIG. 40corresponds to Embodiment 29, (a) of FIG. 41 corresponds to Embodiment30, (b) of FIG. 41 corresponds to Embodiment 31, and FIG. 42 correspondsto Embodiment 32.

FIG. 43 to FIG. 45 are graphs of light transmittances of Embodiment 28to Embodiment 32, wherein (a) of FIG. 43 corresponds to Embodiment 28,(b) of FIG. 43 corresponds to Embodiment 29, (a) of FIG. 44 correspondsto Embodiment 30, (b) of FIG. 44 corresponds to Embodiment 31, and FIG.45 corresponds to Embodiment 32.

FIG. 46 is a graph of a photoluminescence (PL) according to Embodiments28, 29, and 32, wherein (a) of FIG. 46 corresponds to Embodiment 28, (b)of FIG. 46 corresponds to Embodiment 29, (c) of FIG. 46 corresponds toEmbodiment 32.

FIG. 47 is a graph of a sheet resistance with respect to time, accordingto each of Embodiment 28 to Embodiment 32.

The invention claimed is:
 1. A core-shell nanowire, comprising: ananowire core having a plurality of faces; and a metal-compound shellformed on each face of the nanowire core, wherein, when the core-shellnanowire is coated on a transparent substrate to have a sheet resistanceof 1˜100(Ω/□), a haze of the transparent substrate is in a range of 5%or more at a wavelength of 550 nm, and wherein, the metal-compound shellis an aggregate of metal-compound particles having diameters in a rangeof 10 to 100 nm.
 2. The core-shell nanowire according to claim 1,wherein the metal-compound shell comprises a transparent conductivemetal-compound material.
 3. The core-shell nanowire according to claim1, wherein the metal-compound shell has a plurality of protrudedstructures when viewed in a cross-sectional view perpendicular to alength direction of the core-shell nanowire, and an area or a width ofthe protruded structure gradually decreases as the distance from thenanowire core increases.
 4. The core-shell nanowire according to claim1, wherein the metal-compound shell has a shape of a plurality ofpolygons when viewed in a cross-sectional view perpendicular to a lengthdirection of the core-shell nanowire.
 5. The core-shell nanowireaccording to claim 4, wherein each polygon of the metal-compound shellis a triangular shape or a trapezoid shape.
 6. The core-shell nanowireaccording to claim 1, wherein the metal-compound shell has a stripepattern having a plurality of portions extending a longitudinaldirection of the nanowire core.
 7. The core-shell nanowire according toclaim 3, wherein the number of the plurality of protruded structuresviewed in the cross-sectional is three to six.
 8. The core-shellnanowire according to claim 4, wherein the number of the plurality ofpolygons viewed in the cross-sectional is three to six.
 9. Thecore-shell nanowire according to claim 6, wherein the number of theplurality of portions constituting the stripe pattern is three to six.10. The core-shell nanowire according to claim 4, wherein, when a sideof each polygon adjacent to the nanowire core is a bottom side of thepolygon, the bottom side of the polygon has a length (d) of 40 nm to 200nm and a height (c) of 10 nm to 200 nm.
 11. The core-shell nanowireaccording to claim 1, wherein the core-shell nanowire has a length (a)of in a range of 10 μm˜300 μm.
 12. The core-shell nanowire according toclaim 4, wherein a ratio (c/a) of the height (c) of one of the polygonsto a length (a) of the core-shell nanowire is in a range of 0.00006 to0.02.
 13. The core-shell nanowire according to claim 4, wherein a ratio(f/a) of a longest diameter (f) of one of the polygons, when viewed inthe cross-sectional view perpendicular to the longitudinal direction ofthe core-shell nanowire, to a length (a) of the core-shell nanowire isin a range of 0.0001 to 0.06.
 14. The core-shell nanowire according toclaim 1, wherein the haze is in a range of 20% or more at the wavelengthof 550 nm.
 15. The core-shell nanowire according to claim 1, wherein,when the core-shell nanowire is coated on a transparent substrate tohave a sheet resistance of 1˜100(Ω/□), a light transmittance is in arange of 60 to 98% at a wavelength of 550 nm.
 16. The core-shellnanowire according to claim 1, wherein the metal-compound shell includesat least one selected from a group consisting of ZnO, SiO₂, SnO₂, TiO₂,AlN, GaN, BN, InN, ZnS, CdS, ZnSe, ZnTe, CdSe, and carbon.
 17. Thecore-shell nanowire according to claim 1, wherein the nanowire corecomprises at least two wire portions, and wherein an angle (α) betweenan n-th wire portion and an (n+1)th wire portion connected to the n-thwire portion through an n-th bent portion satisfies an inequation of0<α<180°.
 18. The core-shell nanowire according to claim 17, wherein theangle (α) between the n-th wire portion and the (n+1)th wire portionsatisfies an inequation of 130≤α≤170°.
 19. The core-shell nanowireaccording to claim 18, further comprising: an (n+2)th wire portionconnected to the (n+1)th wire portion through an (n+1)th bent portion,wherein, when a plane comprising the nth wire portion and the (n+1)thwire portion is an A plane and a plane comprising the (n+1)th wireportion and the (n+2)th wire portion is a B plane, an angle (β) of the Bplane with respect to the A plane is in a range of −10° to 10°.
 20. Thecore-shell nanowire according to claim 1, wherein the nanowire corecomprises at least two wire parts, the nanowire core comprises an n-thwire part and an (n+1)th wire part connected to the n-th wire part, anda diameter of the n-th wire part is different from a diameter of the(n+1)th wire part.
 21. The core-shell nanowire according to claim 1,wherein the nanowire core comprises a first wire part having a firstdiameter, and a second wire part having a second diameter and extendedfrom the first wire part, and the first diameter is different from thesecond diameter.
 22. The core-shell nanowire according to claim 21,wherein the second wire part is formed at one end or both ends of thefirst wire part.
 23. The core-shell nanowire according to claim 21,wherein the first diameter is in a range of 50 to 100 nm, and the seconddiameter is in a range of 150 to 1100 nm.
 24. A transparent electrode,comprising: a conductor layer comprising the core-shell nanowire ofclaim 1; and a transparent electrode layer formed on the conductorlayer.
 25. The transparent electrode according to claim 24, wherein themetal-compound shell has a plurality of protruded structures when viewedin a cross-sectional view perpendicular to a length direction of thetransparent electrode, and an area or a width of the protruded structuregradually decreases as the distance from the nanowire core increases.26. The transparent electrode according to claim 24, wherein thenanowire core comprises at least one wire portion, and wherein an angle(α) between an n-th wire portion and an (n+1)th wire portion connectedto the n-th wire portion through an n-th bent portion satisfies aninequation of 130°≤α≤170°.
 27. The transparent electrode according toclaim 24, wherein the nanowire core comprises at least one wire part,the nanowire core comprises an n-th wire part and an (n+1)th wire partconnected to the n-th wire part, and a first diameter of the n-th wirepart is different from a first diameter of the (n+1)th wire part.
 28. Anorganic light emitting diode, comprising: a transparent substrate; afirst electrode provided on the transparent substrate; a secondelectrode facing the first electrode; and an organic light emittinglayer provided between the first electrode and the second electrode,wherein the first electrode comprises a transparent electrode accordingto claim 24.